Influence of the water vapour content in air on the high temperature oxidation of cobalt-based alloys part 2: results in wet air

摘要

This second part of the work carried out on the possible influence of water vapour in air on the high temperature oxidation of chromium-rich cobalt-based alloys presents the results obtained for their exposure during 46 hours at1000,1100 and 1200℃ in 10%H_2O-containing air. Post-mortem characterization of the nine samples oxidized in wet air was carried out and the results compared to the ones obtained in dry air and already presented in the first part. The oxide scale spallation tended to be more severe here in wet air, notably for the carbide-free Co-10Ni-30Cr alloy. No significant differences were seen for the two other alloys. The first observations of the external fineness and morphology of the oxide scale did not reveal fundamental differences. The single point of interest was the chromium on extreme surface which were almost systematically higher after oxidation in wet air than in dry air. Future work is envisaged with higher water vapour content expecting to enhance the possible effect of water vapour.